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<title>FFREE—Free Floating-Point Register </title></head>
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<h1>FFREE—Free Floating-Point Register</h1>
<table>
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<th>Opcode</th>
<th>Instruction</th>
<th>64-Bit Mode</th>
<th>Compat/Leg Mode</th>
<th>Description</th></tr>
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<td>DD C0+i</td>
<td>FFREE ST(i)</td>
<td>Valid</td>
<td>Valid</td>
<td>Sets tag for ST(i) to empty.</td></tr></table>
<h2>Description</h2>
<p>Sets the tag in the FPU tag register associated with register ST(i) to empty (11B). The contents of ST(i) and the FPU stack-top pointer (TOP) are not affected.</p>
<p>This instruction’s operation is the same in non-64-bit modes and 64-bit mode.</p>
<h2>Operation</h2>
<pre>TAG(i) ← 11B;</pre>
<h2>FPU Flags Affected</h2>
<p>C0, C1, C2, C3 undefined.</p>
<h2>Floating-Point Exceptions</h2>
<p>None</p>
<h2>Protected Mode Exceptions</h2>
<table class="exception-table">
<tr>
<td>#NM</td>
<td>CR0.EM[bit 2] or CR0.TS[bit 3] = 1.</td></tr>
<tr>
<td>#MF</td>
<td>If there is a pending x87 FPU exception.</td></tr>
<tr>
<td>#UD</td>
<td>If the LOCK prefix is used.</td></tr></table>
<h2>Real-Address Mode Exceptions</h2>
<p>Same exceptions as in protected mode.</p>
<h2>Virtual-8086 Mode Exceptions</h2>
<p>Same exceptions as in protected mode.</p>
<h2>Compatibility Mode Exceptions</h2>
<p>Same exceptions as in protected mode.</p>
<h2>64-Bit Mode Exceptions</h2>
<p>Same exceptions as in protected mode.</p></body></html>